関節リウマチ治療薬の副作用警告/米国医療事情 FDA

 関節リウマチの治療薬の副作用について、FDAは強い警告をだした。免疫系を抑制することで作用する薬剤である、Enbrel、Remicade、Humira、Cimzia について、致命的な感染症リスクがあるという。
 ヒストプラスマ症と呼ばれる真菌症の一種で見逃されやすいためにFDAが懸念している。240例が報告され、45人が死亡し、死亡率は約20%あった。
 インフルエンザ様症状の感染で、中央部地域に流行する。発見が遅れ、呼吸器から他の器官に感染が広がると重症化する。持続的な熱と咳、息切れや疲れやすさといった症状がある場合は真菌感染の可能性がある。
 真菌感染が疑われたら積極的に治療をするようにとFDAは勧めているが、抗真菌薬は副作用も強いのが問題となる。
 4つの薬はTNF-α遮断薬として知られているクラスに属していて、リューマチ性関節炎、クローン病、若年性関節炎、一定のタイプの乾癬、および他の免疫系疾患を治療するために使われている。すべては注射薬である。
 FDA はまた、4つの医薬品とガンとの関連を調査している。18才以下の若年者で治療を開始した患者に、リンパ腫の報告が30例あった。
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FDA orders stronger warnings for 4 arthritis drugs
http://www.nytimes.com/aponline/health/AP-FDA-Arthritis-Drugs.html

By THE ASSOCIATED PRESS
Published: September 4, 2008

Filed at 5:54 p.m. ET

WASHINGTON (AP) -- The Food and Drug Administration ordered stronger warnings Thursday on four medications widely used to treat rheumatoid arthritis and other serious illnesses, saying they can raise the risk of possibly fatal fungal infections.

The drugs -- Enbrel, Remicade, Humira and Cimzia -- work by suppressing the immune system to keep it from attacking the body. For patients with rheumatoid arthritis, the treatment provides relief from swollen and painful joints, but it's ''a double-edged sword,'' said the FDA's Dr. Jeffrey Siegel. That's because the drugs also lower the body's defenses to various kinds of infections.

Siegel, who heads the office that oversees arthritis drugs, said the FDA became concerned after discovering that doctors seemed to be overlooking a particular kind of fungal infection called histoplasmosis. Of 240 cases reported to the FDA in which patients taking one of the four drugs developed this infection, a total of 45 died -- about 20 percent.

The infection, which mimics the flu, is prevalent in much of the middle part of the country. It can have particularly grave consequences if it isn't caught early and spreads beyond the respiratory system to other organs of the body.

Siegel said the investigation began with a single case of a woman taking one of the drugs who died of histoplasmosis. Delving into the case, doctors at the FDA found that the woman had been sick with the fungal infection for a long time. ''This case led us to be concerned that there may be other situations in which physicians may not recognize histoplasmosis,'' said Siegel.

FDA officials searched the agency's database and found the 240 cases of patients taking the medications who had also developed the fungal infection. Of those, at least 21 appeared to involve a late diagnosis, and 12 of them -- more than half -- ultimately died.

Siegel said the FDA's order Thursday means that the risk of histoplasmosis will be flagged in a ''black box,'' the strongest warning information in a drug's prescribing literature. The four medications already have black box warnings about the risk of infections, but the language varies from drug to drug.

Patients should call their doctors if they develop persistent fever, cough, shortness of breath or fatigue, which can be signs of the fungal infection.

And the FDA is also urging doctors to consider aggressive use of antifungal drugs in patients who develop such symptoms, even if the infection has not been confirmed by a laboratory test. Siegel said such a decision should not be taken lightly, since antifungal drugs can also have dangerous side effects. Doctors should consider stopping treatment with the immune-suppressing drugs if patients develop infections.

The four drugs belong to a class known as TNF-alpha blockers, and are considered a mainstay for treating rheumatoid arthritis, a disabling disease in which the immune system attacks the joints. They are also used to treat Crohn's disease, juvenile arthritis, certain types of psoriasis, and other immune system disorders. All are taken by injection.

Separately, the FDA is investigating a possible link between the four medications and cancer in young patients. The agency said earlier this year it has received 30 reports of cancers, mainly lymphomas, in patients who began taking the medications when they were 18 or younger. That investigation is expected to take the rest of the year.

Three of the drugs, Enbrel, Humira and Remicade, are considered blockbusters, with sales of over $1 billion annually for each. Cimzia is newer and less widely used.

Humira is sold by North Chicago, Ill.-based Abbott Laboratories Inc; Cimzia by Belgium-based UCB; Enbrel by Thousand Oaks, Calif.-based Amgen Inc. and Madison, N.J.-based Wyeth; and Remicade by Horsham, Pa.-based Centocor, a unit of Johnson & Johnson, and Kenilworth, N.J.-based Schering-Plough Inc.

Abbott shares fell $1.36, or 2.4 percent, to close at $56.64 Thursday; Amgen fell $2.22, or 3.5 percent, to $60.88; Wyeth fell $1.54, or 3.6 percent, to $41.47; and Johnson & Johnson fell $1.06 to $70.45.

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On the Net: http://tinyurl.com/6aw662

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この記事へのコメント

しがないリウマチ患者
2008年09月10日 21:00
初めまして。
リウマチ患者でエンブレルを使った治療を受けております。
真菌症をはじめとする感染症には注意するよう言われておりますが、真菌症というものがこれほど恐いものだということは、この記事を読んで理解することができました。
体調に充分注意を払いつつ、使用しようと思います。
ありがとうございました。

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